359 lines
11 KiB
C++
359 lines
11 KiB
C++
/*
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* Brickworks
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*
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* Copyright (C) 2022, 2023 Orastron Srl unipersonale
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*
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* Brickworks is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 3 of the License.
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*
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* Brickworks is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Brickworks. If not, see <http://www.gnu.org/licenses/>.
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*
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* File author: Stefano D'Angelo
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*/
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/*!
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* module_type {{{ dsp }}}
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* version {{{ 1.0.0 }}}
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* requires {{{ bw_common }}}
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* description {{{
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* Pinking filter.
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*
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* This is a
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* <a href="https://en.wikipedia.org/wiki/Linear_time-invariant_system"
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* target="_blank">linear time-invariant filter</a> approximately attenuating
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* 3 dB/oct from about 0.000046 × Nyquist frequency to about 0.9 × Nyquist
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* frequency. It can be used to turn white noise into pink noise (hence the
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* name).
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* }}}
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* changelog {{{
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* <ul>
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* <li>Version <strong>1.0.0</strong>:
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* <ul>
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* <li><code>bw_pink_filt_process()</code> and
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* <code>bw_pink_filt_process_multi()</code> now use
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* <code>size_t</code> to count samples and channels.</li>
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* <li>Added more <code>const</code> specifiers to input
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* arguments.</li>
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* <li>Moved C++ code to C header.</li>
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* <li>Added overladed C++ <code>process()</code> function taking
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* C-style arrays as arguments.</li>
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* <li>Removed usage of reserved identifiers.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.6.0</strong>:
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* <ul>
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* <li>Removed dependency on bw_config.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.5.0</strong>:
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* <ul>
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* <li>Added <code>bw_pink_filt_process_multi()</code>.</li>
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* <li>Added C++ wrapper.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.4.0</strong>:
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* <ul>
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* <li>Fixed unused parameter warnings.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.3.0</strong>:
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* <ul>
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* <li>Fixed <code>bw_pink_filt_set_sample_rate_scaling()</code>
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* definition.</li>
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* <li>Added missing documentation for
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* <code>bw_pink_filt_coeffs</code>.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.2.0</strong>:
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* <ul>
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* <li>Refactored API.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.1.0</strong>:
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* <ul>
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* <li>First release.</li>
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* </ul>
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* </li>
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* </ul>
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* }}}
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*/
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#ifndef BW_PINK_FILT_H
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#define BW_PINK_FILT_H
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#include <bw_common.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*! api {{{
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* #### bw_pink_filt_coeffs
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* ```>>> */
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typedef struct bw_pink_filt_coeffs bw_pink_filt_coeffs;
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/*! <<<```
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* Coefficients and related.
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*
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* #### bw_pink_filt_state
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* ```>>> */
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typedef struct bw_pink_filt_state bw_pink_filt_state;
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/*! <<<```
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* Internal state and related.
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*
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* #### bw_pink_filt_init()
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* ```>>> */
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static inline void bw_pink_filt_init(bw_pink_filt_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Initializes input parameter values in `coeffs`.
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*
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* #### bw_pink_filt_set_sample_rate()
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* ```>>> */
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static inline void bw_pink_filt_set_sample_rate(bw_pink_filt_coeffs *BW_RESTRICT coeffs, float sample_rate);
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/*! <<<```
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* Sets the `sample_rate` (Hz) value in `coeffs`.
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*
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* #### bw_pink_filt_reset_state()
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* ```>>> */
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static inline void bw_pink_filt_reset_state(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state);
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/*! <<<```
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* Resets the given `state` to its initial values using the given `coeffs`.
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*
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* #### bw_pink_filt_process1()
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* ```>>> */
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static inline float bw_pink_filt_process1(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, float x);
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static inline float bw_pink_filt_process1_scaling(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, float x);
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/*! <<<```
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* These function process one input sample `x` using `coeffs`, while using
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* and updating `state`. They return the corresponding output sample.
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*
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* In particular:
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* * `bw_pink_filt_process1()` assumes that sample rate scaling is disabled;
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* * `bw_pink_filt_process1_scaling()` assumes that sample rate scaling is
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* enabled.
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*
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* #### bw_pink_filt_process()
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* ```>>> */
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static inline void bw_pink_filt_process(bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, const float *x, float *y, size_t n_samples);
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/*! <<<```
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* Processes the first `n_samples` of the input buffer `x` and fills the
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* first `n_samples` of the output buffer `y`, while using `coeffs` and
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* both using and updating `state`.
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*
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* #### bw_pink_filt_process_multi()
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* ```>>> */
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static inline void bw_pink_filt_process_multi(bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state * const *BW_RESTRICT state, const float * const *x, float **y, size_t n_channels, size_t n_samples);
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/*! <<<```
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* Processes the first `n_samples` of the `n_channels` input buffers `x` and
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* fills the first `n_samples` of the `n_channels` output buffers `y`, while
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* using the common `coeffs` and both using and updating each of the
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* `n_channels` `state`s.
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*
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* #### bw_pink_filt_set_sample_rate_scaling()
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* ```>>> */
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static inline void bw_pink_filt_set_sample_rate_scaling(bw_pink_filt_coeffs *BW_RESTRICT coeffs, char value);
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/*! <<<```
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* Sets whether the output should be scaled (`value` non-`0`) or not (`0`)
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* according to the sample rate in `coeffs`.
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*
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* In order to keep the magnitude response consistent at different sample
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* rates, the output of this filter should be accordingly scaled. The 44100
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* Hz sample rate is used as a reference (that is, the scaling factor at that
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* sample rate is `1.f`).
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*
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* Default value: `0` (off).
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*
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* #### bw_pink_filt_get_scaling_k()
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* ```>>> */
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static inline float bw_pink_filt_get_scaling_k(const bw_pink_filt_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Returns the sample rate scaling factor that is applied or would be applied
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* if sample rate scaling were enabled, as stored in `coeffs`.
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* }}} */
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#ifdef __cplusplus
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}
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#endif
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/*** Implementation ***/
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/* WARNING: This part of the file is not part of the public API. Its content may
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* change at any time in future versions. Please, do not use it directly. */
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct bw_pink_filt_coeffs {
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// Coefficients
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float scaling_k;
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// Parameters
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float sample_rate_scaling;
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};
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struct bw_pink_filt_state {
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float s1_z1;
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float s2_z1;
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float s3_z1;
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float s4_z1;
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};
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static inline void bw_pink_filt_init(bw_pink_filt_coeffs *BW_RESTRICT coeffs) {
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coeffs->sample_rate_scaling = 0;
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}
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static inline void bw_pink_filt_set_sample_rate(bw_pink_filt_coeffs *BW_RESTRICT coeffs, float sample_rate) {
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coeffs->scaling_k = 210.f / bw_sqrtf(sample_rate);
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}
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static inline void bw_pink_filt_reset_state(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state) {
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(void)coeffs;
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state->s1_z1 = 0.f;
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state->s2_z1 = 0.f;
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state->s3_z1 = 0.f;
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state->s4_z1 = 0.f;
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}
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static inline float bw_pink_filt_process1(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, float x) {
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(void)coeffs;
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const float s1 = 0.320696754235142f * x + state->s1_z1;
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state->s1_z1 = 0.999760145116749f * s1 - 0.3204568993518913f * x;
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const float s2 = 0.2870206617007935f * s1 + state->s2_z1;
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state->s2_z1 = 0.9974135207366259f * s2 - 0.2844341824374191f * s1;
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const float s3 = 0.2962862885898576f * s2 + state->s3_z1;
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state->s3_z1 = 0.9687905029568185f * s3 - 0.265076791546676f * s2;
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const float s4 = 0.3882183163519794f * s3 + state->s4_z1;
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state->s4_z1 = 0.6573784623288251f * s4 - 0.04559677868080467 * s3;
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return s4;
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}
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static inline float bw_pink_filt_process1_scaling(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, float x) {
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(void)coeffs;
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return coeffs->scaling_k * bw_pink_filt_process1(coeffs, state, x);
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}
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static inline void bw_pink_filt_process(bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, const float *x, float* y, size_t n_samples) {
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if (coeffs->sample_rate_scaling)
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for (size_t i = 0; i < n_samples; i++)
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y[i] = bw_pink_filt_process1_scaling(coeffs, state, x[i]);
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else
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for (size_t i = 0; i < n_samples; i++)
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y[i] = bw_pink_filt_process1(coeffs, state, x[i]);
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}
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static inline void bw_pink_filt_process_multi(bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state * const *BW_RESTRICT state, const float * const *x, float **y, size_t n_channels, size_t n_samples) {
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for (size_t i = 0; i < n_channels; i++)
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bw_pink_filt_process(coeffs, state[i], x[i], y[i], n_samples);
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}
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static inline void bw_pink_filt_set_sample_rate_scaling(bw_pink_filt_coeffs *BW_RESTRICT coeffs, char value) {
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coeffs->sample_rate_scaling = value;
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}
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static inline float bw_pink_filt_get_scaling_k(const bw_pink_filt_coeffs *BW_RESTRICT coeffs) {
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return coeffs->scaling_k;
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}
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#ifdef __cplusplus
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}
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#include <array>
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namespace Brickworks {
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/*** Public C++ API ***/
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/*! api_cpp {{{
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* ##### Brickworks::PinkFilt
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* ```>>> */
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template<size_t N_CHANNELS>
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class PinkFilt {
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public:
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PinkFilt();
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void setSampleRate(float sampleRate);
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void reset();
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void process(
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const float * const *x,
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float **y,
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size_t nSamples);
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void process(
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std::array<const float *, N_CHANNELS> x,
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std::array<float *, N_CHANNELS> y,
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size_t nSamples);
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void setSampleRateScaling(bool value);
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float getScalingK();
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/*! <<<...
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* }
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* ```
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* }}} */
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/*** Implementation ***/
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/* WARNING: This part of the file is not part of the public API. Its content may
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* change at any time in future versions. Please, do not use it directly. */
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private:
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bw_pink_filt_coeffs coeffs;
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bw_pink_filt_state states[N_CHANNELS];
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bw_pink_filt_state *statesP[N_CHANNELS];
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};
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template<size_t N_CHANNELS>
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inline PinkFilt<N_CHANNELS>::PinkFilt() {
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bw_pink_filt_init(&coeffs);
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for (size_t i = 0; i < N_CHANNELS; i++)
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statesP[i] = states + i;
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}
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template<size_t N_CHANNELS>
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inline void PinkFilt<N_CHANNELS>::setSampleRate(float sampleRate) {
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bw_pink_filt_set_sample_rate(&coeffs, sampleRate);
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}
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template<size_t N_CHANNELS>
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inline void PinkFilt<N_CHANNELS>::reset() {
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for (size_t i = 0; i < N_CHANNELS; i++)
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bw_pink_filt_reset_state(&coeffs, states + i);
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}
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template<size_t N_CHANNELS>
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inline void PinkFilt<N_CHANNELS>::process(
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const float * const *x,
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float **y,
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size_t nSamples) {
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bw_pink_filt_process_multi(&coeffs, statesP, x, y, N_CHANNELS, nSamples);
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}
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template<size_t N_CHANNELS>
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inline void PinkFilt<N_CHANNELS>::process(
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std::array<const float *, N_CHANNELS> x,
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std::array<float *, N_CHANNELS> y,
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size_t nSamples) {
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process(x.data(), y.data(), nSamples);
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}
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template<size_t N_CHANNELS>
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inline void PinkFilt<N_CHANNELS>::setSampleRateScaling(bool value) {
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bw_pink_filt_set_sample_rate_scaling(&coeffs, value);
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}
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template<size_t N_CHANNELS>
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inline float PinkFilt<N_CHANNELS>::getScalingK() {
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return bw_pink_filt_get_scaling_k(&coeffs);
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}
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}
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#endif
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#endif
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